S-layer (glycosylation) impact on Tannerella biofilm
Abstract
Impact of the S layer and its glycosylation on the biofilm lifestyle of the periodontal pathogen Tannerella forsythia The investigation of the pathogenic mechanisms employed by key periodontal pathogens is of bio¬medical relevance. Progression of oral disease is often dependent upon accumulation of oral plaque, a prime example of a bacterial biofilm. Establishing the mechanisms involved in formation and pro¬gression of both mono- and multispecies oral biofilms may pinpoint new targets for interfering with the pathogens’ ability to establish biofilm formation and, eventually, infection in periodontal disease. T. forsythia is an anaerobic, oral pathogen classified as a late colonizer of multispecies-gingival plaque biofilms that constitutes the focus of this research project. It was shown at the host research institution that T. forsythia possesses a so far unique cell envelope that is represented by a 2D crystalline S-layer formed by co-assembly of two S layer glycoproteins (TfsA, TfsB) which are modified with distinct oligosaccharides. This is of special interest considering the importance of bacterial cell surface structures for the development and/or architecture of biofilms. In fact, the S-layer glycoproteins and a predicted export system are up-regulated under biofilm conditions. Our preliminary data indicate that TfsB reduces intraspecies cell aggregation while enhancing surface attachment; a defined truncation of the S-layer glycan resulting in loss of net negative charge promotes biofilm formation. This indicates a distinct regulation between S-layer biosynthesis, glycosylation and biofilm formation. Investigating the influence of the cell surface structures of T. forsythia on biofilm formation is an ideal starting point to gain a more detailed insight into the complex scenario of oral biofilm communities. We hypothesize that the T. forsythia S layer and its glycosylation status, representing the immediate contact zone of the bacterium with its environment, affect the bacterial intra- and inter-species communication in the oral cavity as a prerequisite for the biofilm lifestyle, and, consequently, the ability to establish periodontal infection. Investigating the biochemical and molecular basis for this phenomenon, will increase our understanding of the role of T. forsythia in periodontal disease. As a way to test our hypothesis, the research goals of this proposal are 1) determination of optimal biofilm conditions for T. forsythia wild-type cells, testing different substrates and environmental factors; 2) investigation of the effect of the T. forsythia S layer, its glycosylation and specific components thereof on biofilm formation with a focus on the initial attachment step; 3) analysis of the impact of the T. forsythia S-layer (glycosylation) on the development of multispecies biofilms. Respective T. forsythia S-layer and glycosylation mutants (focusing on the modified pseudaminic acid – a frequent adhesin of pathogenic bacteria - and the N acetylmannosaminuronic acid residues of the S-layer glycan, both contributing to a net charge of the bacterial cell surface) as well as recombinant S layer proteins and purified S layer glycan are available.
keywords Biofilm formation S-layer Pathogenicity Glycosylation Interspecies communication
Publikationen
Glycobiology aspects of the periodontal pathogen Tannerella forsythia
Autoren: Posch, G; Sekot, G; Friedrich, V; Megson, Z A; Koerdt, A; Messner, P; Schäffer C. Jahr: 2012
Journal articles
Project staff
BOKU partners
External partners
Max-Planck Institute of Terrestrial Microbiology
Dr. Kai Thormann
partner